SH.VIII.E.K1

From the FAA library

• Helicopter Flying Handbookp. 11-9
  Chapter 11: Helicopter Emergencies and Hazards › Vortex Ring State

  helicopter begins to descend vertically, it settles into its own downwash, which greatly enlarges the tip vortices. In this vortex ring state, most of the power developed by the engine is wasted in circulating the air in a doughnut pattern ... result, the airflow of the inner blade sections is upward relative to the disk. This produces a secondary vortex ring in addition to the normal tip vortices. The secondary vortex ring is generated about the point on the blade where…

• Helicopter Flying Handbookp. 11-20
  Chapter 11: Helicopter Emergencies and Hazards › System Malfunctions › Tail Rotor Vortex Ring State (210–330°)

  imperative to maintain positive control of the yaw rate and devote full attention to flying the helicopter. Tail Rotor Vortex Ring State (210–330°) Winds within this region cause a tail rotor vortex ring state to develop. [Figure ... result is a nonuniform, unsteady flow into the tail rotor. The vortex ring state causes tail rotor thrust variations, which result in yaw deviations. The net effect of the unsteady flow is an oscillation of tail rotor thrust. Rapid…

• Aviation Maintenance Technician Handbook - Powerplantp. 1-13
  Chapter 1: Aircraft Engines › Piston Rings › Piston Ring Construction

  Piston Rings The piston rings prevent leakage of gas pressure from the combustion chamber and reduce to a minimum the seepage of oil into the combustion chamber. [Figure 1-15] The rings fit into the piston grooves but spring ... press against the cylinder walls; when properly lubricated, the rings form an effective gas seal. Piston Ring Construction Most piston rings are made of high-grade cast iron. [Figure 1-14] After the rings are made, they are ground…